Panoramic camera

ABSTRACT

A panoramic camera has a camera housing rotatable about an axis of rotation that defines a viewpoint which points along a radial optical path that object rays traverse as the camera is rotated about its axis; a lens assembly having an optical path and a front nodal point mounted for rotation with the camera housing with the optical path of the lens offset from the radial optical path; a specular assembly including an object specular member along the radial optical path mounted for rotation with the housing that cooperates with the lens assembly for gathering object rays that traverse the radial optical path and for deviating them along the optical path of the lens assembly in such a way that the front nodal point of the lens subassembly virtually appears to lie on the axis of rotation thereby eliminating image smearing; and has different ambient light responsive controller embodiments operative either to continuously vary or to preset exposure, or to base exposure on a control sinewave whose phase is obtained either automatically via table look up of latitude or longitude coordinates or via GPS input or manually from a sun protractor and whose amplitude is obtained either automatically from the same information and/or manually by operator keypad input. Means are disclosed for allowing the selection of different near- and far-field object distances and for allowing framing (both vertical and angular) of the panoramic subject. In one embodiment, the specular assembly has object and lens mirrors that pivot between open and closed positions. Different embodiments have film or digital image recording devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of allowed, U.S. utilitypatent application Ser. No. 08/320,455 entitled Panoramic Camera, filedOct. 11, 1994, now U.S. Pat. No. 5,659,804, and is related to divisionalapplication entitled Panoramic Camera filed on even date herewith ofU.S. utility application Ser. No. 08/320,455, now U.S. Pat. No.5,758,199, both of which are of the same inventive entity as herein.

FIELD OF THE INVENTION

This invention is drawn to the field of photography, and moreparticularly, to a novel panoramic camera.

BACKGROUND OF THE INVENTION

Panoramic cameras are called upon to provide images over three hundredand sixty (360) degrees of selected near and far-field subjects in sucha manner that the images recorded thereby are substantially free fromsmearing as the camera pans the subject and are neither underexposed noroverexposed given the way the ambient light illuminating the subject mayvary at different angular positions about the three hundred and sixtydegree pan. To provide the ability to select which vertical portion ofthe subject is to be recorded, provision should be made to allow forframing of the subject. To provide the ability to select the extent ofthe subject that is to be recorded, provision should be made to allowfor the use of different field (or angle) of view lenses, such asfisheye, wide angle, normal and telephoto lenses. If, in addition, sucha camera were portable, rugged, reliable, easy to use, inexpensive,compact, and lightweight, it would appeal both to amateur andprofessional photographers alike.

A periscope-type panorama camera that addresses the problem of imagesmearing is disclosed by McNeil in U.S. Pat. No. 2,794,379. It includesa cylindrical camera body having spaced apart top and bottom circularlyshaped walls that are joined by a cylindrical side wall to provide alight tight enclosure. Film is wrapped along the inside of thecylindrical focal plane of the side wall and a film guide and an advancemechanism are provided to guide and advance the film about thecylindrical focal plane after each exposure.

The top wall is journaled for rotation within the cylindrical side walland has a central post that is keyed to a motor driven axle located atthe center of the cylindrical camera body. As the axle is turned by amotor or other mechanism, the top plate rotates about the axis ofrotation of the axle relative to the cylindrical side wall.

A periscope assembly defining an optical axis is mounted for rotationwith the rotatable top plate of the cylindrical camera body such thatits optical axis is parallel to, radially displaced from and containedin a plane common to it and the central axis of rotation. The periscopeincludes a lens. First and second mirrors each to either side of thelens are adjustably aligned along the optical axis to place its nodalpoints on the axis of rotation for a given focal length and objectdistance.

The lens is mounted in an aperture provided in the top wall of thecylindrical camera body. The focal length of the lens is made equal tothe radius of the cylindrical side wall of the camera body. The radiusof the cylindrical side wall defines the focal length of the lens. Fordifferent focal lengths differently sized housings are required.

The first mirror of the periscope assembly (below the lens) is mountedat forty five degrees to the optical axis in the camera body so as toconfront the rear nodal point of the lens and the cylindrical focalplane. Both the lens and the first mirror must be separately adjusted toalign the virtual image of the rear nodal point on the axis of rotation.To do so, the first mirror is axially adjusted along the optical axisuntil it squarely confronts the cylindrical focal plane and ispermanently keyed into position. The lens is then axially adjusted inits mounting aperture until the distance between its rear nodal pointand the first mirror equals the distance by which the optical androtational axes are displaced. These adjustments are laborious and timeconsuming and require that the cylindrical body be disassembled.

The second mirror of the periscope assembly (above the lens) in oneembodiment is a roof prism that is mounted outside the camera bodyconfronting both the front nodal point of the lens and the subject. Theroof prism is required to reverse the image. In an alternativeembodiment, a mirror is substituted for the roof prism and a relay lensis required to reverse the image. In either embodiment, the element isaxially adjusted until the distance between it and the front nodal pointof the lens is such that the virtual image of the front nodal point ofthe lens appears to lie on the axis of rotation.

To provide for different fields of view, differently sized mirrorsand/or lenses would need to be implemented. The change in the size ofthe first mirror might require a different radial offset between theoptical and rotational axes. Thus a different, specially constructedcamera body would be required. The change in the focal length of thelens could also require a differently sized cylindrical side wall.Again, a specially constructed camera body would be required. The roofprism, or second mirror in the alternate embodiment, excludes a wideangle of view because the optical path is folded across the orientationof the exposure slit. For the mirror embodiment, where the relay lens isrequired to reverse the image, the angle of view is further limitedbecause the combination of lenses excludes far off-axis rays.

No provision is made, or able to be made, for framing the subject. Toprovide for different object distances for a given focal length, thehousing as well as the periscope assembly would need to be disassembled,and two adjustments made for the first mirror and a third adjustmentmade for the second mirror to re-effect the alignments of the virtualpositions of the front and rear nodal points of the lens onto the actualaxis of rotation. No provision is made for the effects of varyingambient lighting conditions as the camera pans the subject.

An underwater panoramic camera that addresses the problem of imagesmearing given an object distance and fixed focal length is disclosed byMcNeil in U.S. Pat. No. 3,141,397. The camera includes a cylindricalcamera body having circular top and bottom plates that are joined by anannular lens that constitutes the side wall of the cylindrical camerabody. An arm having a radially extending lens barrel defining an opticalaxis on one side and a film guide and feed assembly on its other side isrotatably mounted in the cylindrical camera body such that as the lensbarrel end of the arm is turned about the axis of rotation in oneangular direction the film guide and feed assembly on the other side ofthe arm advances film in the opposite angular direction.

The in-line lens system, which includes the expensive and fragileannular lens of the cylindrical side wall of the camera body and theoptical elements of the in-line lens barrel itself, provides a fixedfocal length and a given object distance. To prevent smearing as thein-line barrel pans for a fixed focus and given object distance, thecenter of rotation of the arm is positioned so that the ratio of theeccentricities of the front and rear nodal points of the lens is madeequal to the ratio of the object distance to the image distance.

There is, however, appreciable smearing for subjects at other objectdistances. To prevent smearing for subjects at other object distances,the housing needs to be disassembled and another in-line lens assemblywith the proscribed center of rotation for each different given objectdistance installed. In addition, no provision is made, or able to bemade, for changing the framing of the subject, and no provision is made,or able to be made, for changing the field of view.

The radial dimension of the cylindrical housing body depends on thefixed focal length of the lens. Different focal lengths would thusrequire different, specially manufactured housing bodies. No provisionis made for the effects of varying ambient light as the camera pans.

An in-line panoramic camera with an off-axis lens that addresses theproblem of image smearing is disclosed by Cummins in U.S. Pat. No.3,311,038. The camera is like that of the '397 patent except that it hasa stationary film guide and advance assembly defining an image surfaceand has an arcuate, cylindrical-segment lens that constitutes but a partof the side wall of the camera. As in the '397 patent, the in-linebarrel lens is rotated about a preselected point (center of rotation)that is between the front and rear nodal points of the lens selectedsuch that the ratio of the eccentricities of the front and rear nodalpoints is made equal to the ratio of the object distance to the imagedistance for a given object distance and focal length.

In one embodiment where the rear nodal point of the lens confronts theimage surface, a pair of mirrors is provided therebetween that decreasesthe distance from the center of rotation of the arm of the in-line lensto the image surface by an amount that equals the eccentricity of therear nodal point from the point of rotation of the lens, and in anotherembodiment where the front nodal point confronts the image surface, aprism is provided therebetween that increases the distance from thecenter of rotation of the arm to the focal surface by an amount thatequals the eccentricity of the rear nodal point. In either embodiment,however, different, specially designed and manufactured lens assembliesneed to be provided for different given object distances. The focallength of the lens is made equal to the radius of the stationary filmguide and feed assembly. Different, specially constructed housing bodiesare required for different focal lengths. No provision is made, nor isable to be made, for changing the field of view and/or the framing ofthe subject. No provision is made that accounts for the effects ofvarying ambient light conditions.

An in-line and fixed focus panoramic camera that addresses the problemof controlling exposure for the way the light varies about a panoramicsubject is disclosed by Waroux in U.S. Pat. No. 3,246,588. In oneembodiment, single panoramic images are provided and in another stereopanoramic images. In either embodiment, an in-line lens subassemblyhaving a fixed focus and an optical axis is mounted for rotation with acamera housing with its optical axis offset from a stationary drum of afilm guide and feed subassembly that is journaled for rotation about theaxis of the camera housing. In either embodiment, no provision is madeto take account of the blurring that results from the offset of theoptical axis of the lens subassembly from the axis of rotation and noprovision is made for framing, for different focal lengths and theircorrespondingly different fields (angle) of view, or for selectablenear- and far-field object distances.

To control exposure, in one embodiment one of one or more cams havingdifferently shaped profiles and/or a cam of variable profile ispre-selected to drive the camera housing about its axis of rotation witha speed that corresponds to the profile of the cam selected. In thisembodiment, the cam that is pre-selected is the one that is judged bestin the field to match the prevailing lighting conditions. In anotherembodiment, the cam that is selected is set to control the size of thediaphragm of the lens subassembly rather than the speed of rotation.Again, once selected, the way the diaphragm is varied with angle ispre-set. In a further embodiment, a light meter is used to change eitherthe speed or the size of the diaphragm point-to-point.

SUMMARY OF THE INVENTION

It is accordingly the principal object of the present invention toprovide a panoramic camera that is portable, rugged, reliable, easy touse, inexpensive and compact, lightweight and suitable for use for bothamateur and professional photographers alike; that provides smear-freeimages as it pans about a three hundred and sixty (360) degree arc; thatmay be readily adjusted to accommodate both near- and far-fieldsubjects; that may be readily adjusted to provide selected framing andto accommodate different selectable fields (angle) of view includingvery wide vertical angle lenses; and that automatically and continuallyadjusts for varying ambient light conditions as the camera pansdifferent angular portions of the three hundred and sixty degreesubject.

The panoramic camera of the present invention includes a camera housinghaving a front wall and a rear wall. An axle defining an axis ofrotation is mounted in said camera housing. Means are coupled to saidaxle and said housing for rotating the housing about said axis ofrotation of said axle such that object rays from the panoramic subjecttraverse a radial optical path that extends generally perpendicularlybetween said axis of rotation and that portion of the panoramic subjectconfronting said front wall of the camera housing as the camera housingis rotated about said axis of rotation.

A lens subassembly defining an optical axis and having front and rearnodal points and a focal length is mounted at a predetermined positionfor rotation with said camera housing determined such that the lenssubassembly is remote from said axle with its optical axis in a planedifferent from any plane that contains said axis of rotation and withits optical axis offset from said radial optical path that said objectrays traverse and at a predetermined orientation thereto. In oneembodiment, the orientation is a parallel orientation and in another itis a perpendicular one.

A specular subassembly means having an optical train including an objectspecular member is mounted for rotation with said housing body forgathering said object rays that traverse said radial optical path andfor deviating the same along said optical path of said lens assemblythat is offset from said radial optical path in such a way that saidfront nodal point of said lens subassembly appears to virtually lie onsaid axis of rotation. In one embodiment, the specular subassemblyincludes a lens specular member as well as the object specular member,where the object and lens specular members are mounted for rotation withthe front wall of the camera housing with the object specular memberlying on said radial optical path and confronting the lens specularmember and with the lens specular member lying on the optical axis ofthe lens subassembly and confronting both the object specular member andthe lens subassembly. Means coupled between the members and the housingmove the mirrors between closed and open positions. In anotherembodiment, the object specular member is mounted inside the camerahousing along both said radial optical path and said optical path ofsaid lens subassembly and confronting both the subject and the lenssubassembly. In either embodiment, there is no smearing of the image asthe camera pans the subject because, from the subjects point of view,the lens subassembly appears to rotate about its front nodal point.

Means having an imaging surface are mounted for rotation with saidcamera housing in such position that said imaging surface is remote fromsaid axle and confronts the rear nodal point of said lens subassemblyfor recording images of said panoramic subject imaged thereto by saidlens subassembly. In one embodiment, the recording means includes filmand a cooperative film guide and advance mechanism and in anotherembodiment it includes a digital recording device.

A light sensor means is mounted to said camera housing for providing atleast one signal representative of ambient light intensity. In alternateembodiments, the light sensor means includes a reflected light sensormounted to the front wall of the camera housing, an incident lightsensor mounted to the rear wall of the camera housing, a reflected lightsensor and an incident light sensor mounted respectively to the frontand rear walls of the camera housing and a light sensor mounted on a twodegree of freedom swivel mount operative with a removable diffuser dometo sample light from a generally upward orientation so as to provide ageneral incident light reading, horizontally and away from lensdirection to provide angular phase related incident light reading, andoperative without the removable diffuser dome to sample light from anyarea of the panoramic scene so as to provide a reflected light readingtherefrom. In one embodiment, means are mounted to said camera housingresponsive to said at least one signal and coupled to said rotationmeans for continually varying automatically the speed of rotation ofsaid housing about said axis of rotation in direct relation to themagnitude of said at least one signal. Because the resulting exposureduration is continually varied inversely to the intensity of the ambientlight, both under- and over-exposures are thereby automaticallyeliminated. By regulating the speed by the incident light generatedsignal, rather than by the reflected light generated signal, abruptvariations in scene luminance cause neither abrupt shifts in speed northe consequent exposure banding at the transition points. In anotherembodiment, means are mounted to said camera housing responsive to saidat least one signal and coupled to said rotation means for preselectingthe speed of rotation of said housing about said axis of rotation basedon the magnitude of a single reading of said at least one signal therebyyielding a constant exposure for the entire rotation of the camera. Inyet another embodiment, processor-implemented means are disclosed forproviding a sinewave of one cycle per revolution having an amplitude anda phase, whose amplitude is matched both to ambient lighting conditionsand to the declination of the sun and whose phase is matched to theposition of the sun in the plane of camera rotation relative to thestarting position of the lens, and an exposure controller means,responsive to said sinewave, are disclosed for controllably compensatingexposure for the variations found in lighting about a typical outdoorpanoramic scene. In one embodiment, a sun protractor having pluralconcentric sun declination rings indexed to a plurality of stops ismounted for rotation with the camera housing. The position of the sun inthe plane of camera rotation is read off the protractor and manuallyentered on a keypad. The declination of the sun, and therewith thecorresponding brightness thereof, is read off the appropriate one of theconcentric sun declination rings, and it is entered on the keypad. Inanother embodiment, the position of the sun in the plane of camerarotation is automatically determined from the readings provided by atime and date clock, by an electronic compass indexed to the startingposition of the lens, and from latitude and longitude readings providedeither by a GPS (global positioning satellite system) or by tablelook-up. In this embodiment, the amplitude of the sinewave is determinedby the declination of the sun and may also be manually set by keypadentry for clear, partly cloudy, overcast, deep shade or other suchconditions.

First means are mounted for rotation with the camera housing foradjusting the lateral spacing between said imaging surface of said imagerecording means and said rear nodal point of said lens subassembly andsecond means are mounted for rotation with said camera housing foradjusting the vertical spacing between said imaging surface of saidimage recording means and said rear nodal point of said lenssubassembly. The first adjustment means enables to select any focallength lens and corresponding field of view and to select that imagedistance that corresponds to any selected near- and far-field objectdistance for a given focal length without re-configuring the camerahousing. The second adjustment means enables to provide framing, i.e., aselected vertical shift of the image relative to its horizon.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, aspects and advantageous features of the presentinvention will become apparent as the invention becomes betterunderstood by referring to the following detailed description of thepreferred embodiments thereof and to the drawings, wherein:

FIG. 1 is a schematic cross-sectional view in the FIG. 1A thereof and isa schematic perspective view in the FIG. 1B thereof of a panoramiccamera in accord with the present invention illustrating it in one ofits presently preferred embodiments;

FIG. 2 illustrates schematic plan views in the FIGS. 2A, 2B thereof andillustrates pictorial front views in the FIGS. 2C, 2D thereof that areuseful in explaining the operation of the embodiment of the opticalassembly of FIG. 1;

FIG. 3 is a schematic cross-sectional view of a panoramic camera inaccord with the present invention illustrating it in another of itspresently preferred embodiments;

FIG. 4 is a schematic cross-sectional view of a panoramic camera inaccord with the present invention illustrating it in yet another of itspresently preferred embodiments;

FIG. 5 is a functional block diagram of one embodiment of an ambientlight responsive controller useful with any of the presently preferredembodiments of a panoramic camera or other panoramic camera in accordwith the present invention;

FIG. 6 illustrates plan pictorial diagrams in the FIGS. 6A,6B,6C thereofthat are useful in explaining the operation of the ambient lightresponsive controller of a panoramic camera in accord with the presentinvention;

FIG. 7 is a perspective view of another light sensor system embodimentof a panoramic camera in accord with the present invention;

FIG. 8 is a functional block diagram of yet another embodiment of anambient light responsive controller useful with the light sensor systemof the FIG. 7 of a panoramic camera or other panoramic camera in accordwith the present invention;

FIG. 9 illustrates in the FIG. 9A, FIG. 9B, and 9C diagrams useful inexplaining the principles of "sinewave" ambient light responsiveexposure control of a panoramic camera in accord with the presentinvention;

FIG. 10 is a functional block diagram of one embodiment of a "sinewave"ambient light responsive exposure controller of a panoramic camera inaccord with the present invention;

FIG. 11 is a pictorial view of a sun protractor having declination ringsuseful with the FIG. 10 embodiment of a "sinewave" ambient lightresponsive exposure controller of a panoramic camera in accord with thepresent invention; and

FIG. 12 is a functional block diagram of another embodiment of a"sinewave" ambient light responsive exposure controller of a panoramiccamera in accord with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, generally designated at 10 is one presentlypreferred embodiment of a panoramic camera in accord with the presentinvention. The camera 10 includes a housing generally designated 12having a top wall 14 (FIG. 1B), a bottom wall 16 (FIG. 1B), a front wall18 having an aperture therethrough generally designated 20, a back wall22, and opposing side walls 24,26. Any other suitable housing bodyhaving a front and providing a light-tight enclosure may be employedwithout departing from the inventive concepts.

The housing 12 is journaled for rotation about a vertical axle 28preferably by bearings provided therefor in the top and bottom walls14,16 thereof. The axle 28, which extends between the top and bottomwall 14,16, provides a rigid support about which the camera rotatesabout an axis of rotation 30 as illustrated by an arrow 32 (FIG. 1B).The axle 28 has an end 34 (FIG. 1B) that extends beyond the bottom wall16 of the camera housing 12. The end 34 is mounted to a telescopingshaft 36 of a tripod or other camera support 38 by a releasable lockassembly generally designated 40 (FIG. 1B) or other suitable means.

A motor 42 having a worm gear 44 mounted to its shaft is mounted forrotation with the bottom wall 16 of the housing. A worm wheel gear 46 isconcentrically mounted to the axle 28. As the shaft of the motor 42turns, the drive spindle of the worm gear 44 turns the teeth of the gear46, which rotates the bottom wall 16 about the axle 28 and, with it, thecamera housing 12 about the axis of rotation 30. Any suitable meansother than rotating the camera housing for panning the subject may beemployed, such as rotating a lens and therewith its viewpoint and/orrotating a mirror or other specular assembly, although the presentlypreferred embodiment enjoys the advantage, among others, that the axleand the drive drum to be described mounted for rotation therewith may bereadily replaced with an axle having a drive drum of another radius toaccommodate lenses of various focal lengths and thereby provide anyselected vertical field of view. In addition, by having the drive drumrigidly and directly linked to the worm wheel via the axle, only onegear interface is needed to rotate the housing, which enjoys not onlythe advantages of being light in weight, reliable and inexpensive butalso minimizes gear backlash and therewith exposure irregularities inthe form of banding. A film guide and feed assembly generally designated48 is mounted inside the camera housing 12. The assembly 48 includesfilm supply spool 50 and take-up mechanism 52, a film drive drum 54, anexposure slit 56 and a pair of film guide rollers 58. Film 60 releasedby the film supply mechanism 50 is threaded over the drum 54 through theguide rollers 58 past the exposure slit 56 and into the film take-upmechanism 52 The drive drum is mounted concentric with and fixed to theaxle 28 so that it remains stationary as the housing 12 is turned aboutthe axis of rotation 30 by the motor 42. As the housing 12 rotates aboutthe drum 54, the film 60 is moved past the exposure slit 56 with alinear velocity that depends on the radius of the drive drum 54 and theangular velocity of the panoramic swing of the camera housing 12 aboutthe axis of rotation 30.

An optical assembly generally designated 62 is mounted for rotation withthe camera housing 12. The assembly 62 includes a lens subassembly 64and a specular subassembly generally designated 66, both mounted forrotation with the camera housing 12. The lens subassembly defines anoptical axis, has front and rear nodal points and a focal length and itis mounted inside the housing 12 with its front nodal point confrontingthe aperture 20 and with its rear nodal point confronting the exposureslit 56 of the film feed and guide assembly 48. The specular subassembly66 includes an object mirror 68 and a lens mirror 70 spaced from theobject mirror 68, which are mounted for pivotal movement to the outsideof the front wall 18 of the housing 12 in a manner to be described. Anoptical path from the object mirror 68 to the lens subassembly 64 isprovided by the mirror 68, which confronts the mirror 70 and the object,and by the mirror 70, which confronts both the front nodal point of thelens subassembly 64 and the object mirror 68. Although discrete mirrors68,70 are illustrated, any specular subassembly that provides the sameoptical path, such as a monolithic optical element, may be employed. Thespecular subassembly and/or lens subassembly may be positioned outsideor inside the camera housing alternately without departing from theinventive concepts.

A slide mechanism illustrated schematically by arrow 72 marked "X" iscoupled between each of the rollers of the pair of rollers 58 and thehousing 12 to slidably adjust their position towards and away from therear nodal point of the lens subassembly 64 in the "X" direction and tosecure them in any position selected. A slide mechanism schematicallyillustrated by arrow 74 and marked "Y" is coupled between the lenssubassembly 64 and the housing 12 for adjusting the position of the lenssubassembly 64 vertically in the "Y" direction (in/out of the page).

In the illustrated embodiment, the drive drum 54 on the one hand and theguide rollers 58 and lens subassembly 64 on the other are mounted in thehousing body towards opposing sides thereof, which provides theclearance that allows interference-free adjustment of the slidemechanisms 72,74, although it will be appreciated that other off-setspacing may be employed without departing from the inventive concepts solong as there is sufficient clearance between the guide rollers, thedrive drum and axle, and between the lens subassembly and the drive drumand axle, so as to allow interference-free adjustment of the X,Y slidemechanisms 72,74. It will be appreciated that any suitable mechanismsmay be employed to adjust the relative spacing between the guide rollersand the lens subassembly in the "X" and "Y" directions without departingfrom the inventive concepts.

To ensure perfect synchronization of image speed and film advance, theradius of the drive drum 54 of the film guide and feed assembly 48 isselected to be equal in magnitude to the focal length of the lenssubassembly 64. The offset placement of the drive drum position and ofthe lens subassembly position enables to accept different focal lengthlenses and drive drums with commensurate radii without re-configuringthe camera housing for each different focal length selected. Wide angle,normal and other focal length lens subassemblies may thereby be readilyaccommodated without re-designing the camera housing 12. It should benoted that a pair of symmetrically stepped drums, not shown, may beemployed, where each different step corresponds to another focal lengthlens or object distance that may be selected. The offset placementprovides the clearance that enables the use of the symmetrically steppeddrive drums.

To provide smearing-free exposure of the film 60 as the camera housing12 rotates about the axis of rotation 30, the lens subassembly 64 ispositioned with its rear nodal point spaced from the film a distancethat corresponds to the focal length of the lens subassembly and withits front nodal point spaced from the object mirror 68 along the opticalpath of the specular subassembly 66 a distance that corresponds to thedistance from the object mirror 68 to the axis of rotation 30 of thecamera housing 12. With this arrangement, the front nodal point of thelens subassembly 64 virtually appears, from the point of view of thesubject, to lie on the axis of rotation 30. The image of the subject onthe film 60 thereby appears to be stationary during the time it takes agiven point on the film 60 to traverse the exposure slit 56, therebyproviding smearing-free exposure of the film 60 as the camera housing 12is rotated irregardless of object distance.

To accommodate different near- and far-field subjects at any selectedobject distance, the film guide roller slide mechanisms 72 are laterallyspaced from the lens subassembly 64 at that image distance thatcorresponds to the object distance selected. For any near- and far-fieldobject distance selected, smearing-free exposure of the film 60 isthereby provided at the corresponding image distance withoutre-designing the camera housing 12. For large changes of focus, a drivedrum of the appropriate radius, or a different step on the symmetricallystepped drive drums, may be readily used without re-configuring thecamera housing.

A reflected light sensor 76, such as a narrow angle of acceptancephotocell, is mounted to the front wall 18 of the camera housing 12 andan incident light sensor 78, such as a photocell, is mounted to the backwall 18 of the camera housing 12 under a diffusion dome 80. The sensors76,78 alone and in combination cooperate with one embodiment of anambient light responsive controller to be described to vary the exposuretime of the film 60 in dependence on the variation in ambient lightingconditions encountered across a typical panoramic scene therebypreventing both under- and over-exposure of the film.

Referring now to FIG. 2, the specular subassembly 66 of the opticalassembly 62 in the presently preferred embodiment is mounted to theoutside of the front wall 18 of the camera housing 12 such that theobject and lens specular members 68,70 thereof are movable betweenclosed and open positions. The lateral edge of the member 68 remote fromthe aperture 20 is rotatably mounted on an axle 82 for pivoting motionabout the front wall 18, and the lateral edge of the member 70 proximatethe aperture 20 is rotatably mounted on an axle 84 for pivoting motionabout the front wall 18. The opposing lateral edges of a cover/baffleplate 86 are pivotally mounted to respective ones of the pivotallyswinging edges of the members 68,70 via axles 88,90. An indexing plate92 is rotatably mounted on an axle 94 for pivoting motion about the topwall 14 of the housing 12. Torsion springs, not shown, are mounted aboutthe axles 82,84,94 for biasing the members 68,70 in their normally openconditions where they pivot out from the front wall 18 of the housing 12and for biasing the indexing plate 92 in its normally closed conditionwhere it lies flat against the top wall 14 of the housing 12 (FIG. 2A).A lens cover plate 96 extends beyond the lateral edge of the objectmirror 68 a distance that allows it to cover the confronting face of thelens subassembly 64.

In the normally closed condition of the specular subassembly 66, thecover/baffle plate 86 protects the specular surface of the lens mirror70, the lens cover 96 covers the aperture 20 and lens subassembly 64,and the mirrors 68,70 lie flat against the front wall 18 of the housingas best seen in FIGS. 2A, 2C. In their closed condition, the mirrors68,70 are locked against the front wall of the camera housing by areleasable clamp, not shown.

To open the specular subassembly 66, the clamp is released and theresilience of the torsion springs mounted to the axles 82,84 swings themirrors 68,70 to their open position, while the indexing plate 92 issimultaneously pulled to overcome the resilience of the torsion springmounted to the axle 94 and to swing it away from its normally closedposition. The indexing plate 92 is then positioned over the members68,70. The mirrors 68,70 have projecting tabs which abut the indexingplate 92, locking them in their use condition as best seen in FIGS. 2B,2D.

In the open condition of the specular subassembly 66, cover/baffle plate86 acts as a light baffle, and the indexing plate 92 functions as ashade preventing ghosting and glare.

To return the specular subassembly 66 to its closed condition, themirrors 68,70 are sprung against their bias to release the indexingplate 92, the plate 92 is lifted out of engagement with the specularsubassembly and returned to its normally closed position while the lenscover 96 is pivoted to force the specular members 68,70 to return totheir closed position where they are clamped. Any other suitablemechanism may be employed to move the mirrors between their open andclosed positions.

Referring now to FIG. 3, generally designated at 100 is anotherpresently preferred embodiment of a panoramic camera in accord with thepresent invention. Identical components bear the same numerals as theembodiment 10 of FIG. 1 and are not described again for the sake ofbrevity of disclosure. The embodiment 100 differs from the embodiment 10in three principal respects. The specular subassembly 66 consists of asingle object/lens member 102 that is mounted for rotation with thehousing 12 inside of the camera 100 with its specular surfaceconfronting both the object through aperture 20 thereof and the lenssubassembly 64. As the second respect, one of the guide rollers 58 ofthe film feed and guide assembly 48 is constituted as a film drive drum104 of radius "rf" and a film drive pulley 106 of radius "rp". Thepulley 106 is turned by a belt that loops around pulley 106 and a pulley108, which belt is driven by a stationary pulley 55 as the housing 12 isrotated about the axis 30. The pulley 55 is mounted to the axle 28 sothat it remains stationary as the housing 12 is turned about the axis 30by the motor 42. The stationary pulley 55 has a radius "rs". The focallength of the lens subassembly 64 and the radii of the drum 104 andpulleys 55,106 are selected to satisfy the relation "f/rf=rs/rp" inorder to synchronize film advance and camera angular velocity andthereby prevent image smearing for any focal length "f" that may beselected. As the third respect, the lens subassembly 64 is mounted forsliding motion towards and away from the exposure slit 56 in an "X"direction to provide that image distance that corresponds to anyselected near- and far-field object distance selected and is mounted forsliding motion along a "Y" direction perpendicular to the plane of thepage to provide for framing of the object as schematically illustratedby crossed arrows 110 marked "X" and "Y". Any suitable slide mechanismmay be employed without departing from the inventive concepts.

As in the embodiment 10 of FIG. 1, the distance along the optical pathof the specular subassembly from the object mirror 102 to the frontnodal point of the lens subassembly 64 is made equal to the distancefrom the object/lens mirror 102 to the axis of rotation 30 of the camera100 to prevent smearing of images as the camera is rotated irregardlessof object distance.

The drive pulley 55 and the lens subassembly 64 are mounted towardslaterally opposing sides of the camera housing to provide the clearancethat enables interference-free adjustment of the X and/or Y slidemechanisms 110 to provide the image distance that corresponds to anyselected near- and far-field object distance and that enables to acceptany radii for the drum 104 and pulleys 55,106 that correspond to a givenfocal length of the lens subassembly without reconfiguring the camerahousing 12. In addition, the clearance enables to accept the pair ofsymmetrically opposing stepped drive drums.

Referring now to FIG. 4, generally designated at 112 is anotherpresently preferred embodiment of a panoramic camera in accord with thepresent invention. Identical components bear the same numerals as theembodiment 100 of FIG. 3 and are not described again for the sake ofbrevity of disclosure. The embodiment 110 differs from the embodiment100 in two principal respects. As the first respect, the film feed andguide assembly 48 (FIG. 3) is replaced by a digital recording device114, such as a single-row charge coupled device and its associatedelectronics package 116, mounted for rotation with the housing 12 of thecamera 112. The electronics package 116 typically includes an amplifier,for adjusting the gain of the output signal of the CCD array, and acontrol input for varying the line time (capture rate) of the CCD array.As the second respect, a stationary worm wheel gear 118 is mountedconcentric with and fixed to the axle 28 and is driven by a motor havinga worm gear 120.

As in the embodiment 100 of FIG. 3, the distance along the optical pathof the specular subassembly 66 from the object/lens mirror 102 to thefront nodal point of the lens subassembly 64 is made equal to thedistance from the object/lens mirror 102 to the axis of rotation 30 ofthe camera 112 to prevent smearing of images as the camera is rotatedirregardless of object distance. The electronics package on the one handand the lens subassembly 64 on the other are mounted towards laterallyopposing sides of the camera housing to provide the clearance thatenables interference-free adjustment of the X,Y mechanism(s) 110 toprovide the image distance that corresponds to any selected near- andfar-field object distance in X, that enables to frame the image in Y andthat enables to accept any given focal length of any selected field(angle) of view lens subassembly 64 without re-configuring the camerahousing 12.

Referring now to FIG. 5, generally designated at 130 is a functionalblock diagram of an ambient light responsive controller useful with anyof the presently preferred embodiments of a panoramic camera or otherpanoramic camera in accord with the present invention. The controller130 includes a reflective light sensor 76 mounted to the front wall ofthe camera housing and/or an incident light sensor 78 mounted to therear wall of the camera housing of any embodiment of any panoramiccamera in accord with the present invention.

The reflected light sensor 76 mounted to the front wall of the camerahousing is oriented to always measure the intensity of the lightreflected by the subject 77. As shown in FIGS. 6A, 6B, 6C by thematching shading on the subject 77 and dome 80, the ambient sensor 78 onthe back wall of any presently preferred embodiment or other camera inaccord with the inventive concepts is always oriented so as to sampleambient light corresponding to that on the side of the subject facingthe camera. It will be appreciated that the incident light sensor neednot be mounted on the back wall of the camera housing so long as it isoriented to face away from the pointing direction of the camera in thediametrically opposite direction. It will also be appreciated that thereflected light sensor need not be mounted on the front wall of thecamera housing so long as it faces in the same direction that the camerapoints.

In an alternative embodiment where a motor housing is provided separatefrom the camera chassis, a light sensor may be affixed to the end of astationary, hollow axle to avoid the use of a signal noise generatingcommutator. The stationary, hollow axle extends to the top wall of thecamera housing and to the bottom wall of the motor housing. A gearmounted to the camera chassis is driven by a motor in the motor housingsuch that the camera chassis is rotatably driven about the stationary,hollow axle. The light sensor at the top end of the stationary, hollowaxle is electrically connected to a motor controller to be described bypassing the electrical wires therefrom through the passageway providedby the hollow axle. The light sensor at the top end of the stationary,hollow axle is covered by an interchangeable light modifying memberaffixed to and rotating with the camera chassis. The aforementionedlight modifying member may comprise a diffusion dome with half of itssurface opaqued so as to admit ambient light from one side to provide anincident light sensor system, or a specular member mounted so as todirect reflected light from the scene down to the light sensor toprovide a reflected light sensor system, or a combination employing abeam splitter to reflect object rays to the light sensor (photocell)from a small opening in the opaque side of the dome while transmittingincident light from the translucent side of the dome to provide anincident and reflected light sensor system.

On a typical cloudless daylight scene, proper exposure may vary by asmuch as three (3) stops, or a factor of eight (8), across a threehundred and sixty degree (360) pan, which variation is beyond theexposure latitude of the film. Furthermore, this variation varies as afunction of ambient lighting conditions and cloud conditions, theelevation of the sun, and artificial light, among other things. It alsomay vary during the course of a long exposure. By mounting the incidentlight sensor so that it is always oriented to sample light correspondingto that on the side of the subject facing the camera, these and otherproblems are eliminated. Moreover, the diffusion dome 80, that takes inlight from a broad angle, eliminates abrupt changes in speed (or otherexposure control technique) that may be due to localized bright spots.Furthermore, in the case of backlighting of translucent objects wheretransmitted light becomes a factor, a correcting input as describedbelow may be gained by mixing in the signal from the reflected lightsensor. In general, in scenes involving physical blockages of light,such as a cave, a correcting input from the reflected light sensorserves to boost exposure for unusually dark areas of the scene.

Returning now to FIG. 5, the output signal(s) from the sensors 76,78 is(are) fed to a controller 132, and a motor or other controller 134 isconnected to the output of the controller 132. The controller 132provides a signal to the motor controller 134 in response to the outputsignal(s) of the sensors 76,78 to vary the angular velocity of thecamera so that the exposure time is inversely proportional to lightintensity and is adjusted continuously during rotation for the widelatitude of brightness encountered across a typical panoramic scenethereby always ensuring the correct exposure and therewith eliminatingboth under- and over-exposure. In alternate embodiments, the sensors76,78 may be used singly or in combination, and any suitable weightingof the output signals thereof may be employed when used in combination,without departing from the inventive concepts. In alternativeembodiments, the exposure may be continually adjusted other than byvarying the angular velocity, such as by controllably changing thediaphragm of the lens, by controllably changing the width of theexposure slit, by controllably varying the line time, or by controllablyvarying the gain, without departing from the inventive concepts. In analternative embodiment, the controller 132 reads a value of one or bothof the incident or reflective light sensors 76, 78 and stores it (them)in its memory device, not shown. Based on the stored value(s), thecontroller 132 then provides a signal to the motor controller 134 to fixthe motor speed at a constant speed for the entire rotation yielding aconstant exposure for the entire rotation of the camera. In alternativeembodiments, the exposure may be determined other than by presetting theangular velocity, such as by controllably preselecting the diaphragm ofthe lens, by controllably preselecting the width of the exposure slit,by controllably preselecting the line time, or by controllablypreselecting the gain without departing from the inventive concepts.

Referring now to FIG. 7, generally designated at 150 is a pictorial viewillustrating another embodiment of an ambient light sensor system inaccord with the panoramic camera or other panoramic camera in accordwith the present invention. The ambient light sensor system 150 includesa barrel member 152 mounted to panoramic camera housing schematicallyillustrated at 154 via a two degree of freedom swivel mount generallydesignated 156. The two degree of freedom swivel mount 156 includes afirst rotary joint 158 allowing the barrel member 152 to pivot in avertical plane and a second rotary joint 160 allowing the barrel member152 to pivot in a horizontal plane. Detents, not shown, may be providedto preselect certain positions of the two degree of freedom swivelmount. A light sensor 162 is mounted inside the barrel member 152. Adiffuser dome 164 is removably attachable to the barrel member 162.

The ambient light sensor system 150 is operable in four (4) basic modes.In one mode, the diffuser dome 164 is mounted to the barrel 152, and thebarrel 152 is pivoted about the rotary hinge 158 so as to point thelight sensor 162 thereof generally upwardly. In this mode, the sensor162 is sampling light from a generally upward direction so as to providean incident light reading from which either a fixed exposure ispreselected in a manner to be described over the panoramic scene or avariable exposure is adjusted in a manner to be described for changes inlight which may occur over time, such as when a very long time exposureis made under varying cloud conditions. In another mode, the diffuserdome 164 is mounted to the barrel 152, and the barrel 152 is pivotedabout the rotary hinges 158, 160 so as to point the light sensor 162thereof generally rearwardly (opposite to the direction that the lensfaces). In this mode, the sensor provides an incident light reading fromwhich exposure is continuously adjusted in a manner to be described overthe panoramic scene. In its third mode, the diffusor dome 164 is removedand the barrel 152 is pivoted about the rotary hinges 158, 160 so as topoint the light sensor 162 thereof generally forwardly (in the samedirection that the lens faces). In this mode, the sensor provides areflected light reading from which exposure is continuously adjusted ina manner to be described over the panoramic scene. The fourth mode islike the third, where the diffuser dome is removed from the barrel 152housing the sensor 162, but differs therefrom in that the barrel ispivoted about the rotary hinges 158, 160 so as to point the light sensor162 thereof at any selected angle about the hinge 158, and at anyselected angle about the hinge 160, so as to sample light from anyselected part of the panoramic scene. In this mode, the sensor providesa reflected light reading from which exposure is preselected in a mannerto be described regardless of the starting point of the camera 154;otherwise, the starting point at the beginning and end of the imagewould fix the area sampled even though an area in the middle, forexample, may be preferred.

Referring now to FIG. 8, generally designated at 170 is a functionalblock diagram of an ambient light responsive controller for use with theambient light sensor system 150 (FIG. 7) of a panoramic camera or otherpanoramic camera in accord with the present invention. The controller170 includes a light sensor 172. The output signal of the sensor 172 isfed to a controller 174, and an exposure controller 176 is connected tothe output of the controller 174. In one embodiment, the controller 174provides a signal to the exposure controller 176 in response to theoutput signal of the sensor 172 to continuously vary the exposure duringrotation to account for the wide latitude of brightness encounteredacross a typical panoramic scene thereby always ensuring the correctexposure and therewith eliminating both under- and over-exposure. Inalternative embodiments, the exposure controller 176 may continuouslyvary rotation rate, CCD gain and/or line time (capture rate), oraperture (diaphragm), or slit width. To control the exposure of adigital capture device, such as a CCD, the controller 174 is responsiveto the light sensor signal to continuously vary gain and/or line timeabout the panoramic scene in inverse proportion to light value as thecamera rotates. Gain is increased as light value is decreased. In thecase of line time, this may necessitate or allow a variation of rotationspeed; that is, the rotation speed on the one hand must be reduced toallow for comparatively long line times and on the other hand it may beincreased for comparatively short line times. By matching the motorspeed to the line time, it is possible to minimize capture time for theentire sweep. Alternately, the camera may be rotated at a constant speedto accommodate the longest line time even though a shorter line time maybe in use. That is, if the camera is rotated at a constant speed, theline time is varied in inverse dependence on the light sensor's signalas the camera is swept about the panoramic scene. Several constantspeeds may be provided to accommodate various ranges of line times, suchas indoor or outdoor, while generally limiting total capture time, thetime it takes to capture the entire scene. In another embodiment, thecontroller 174 provides a signal to the exposure controller 176 inresponse to the output signal of the sensor 172 to preset the exposureduring rotation so as to provide a constant exposure for the entirerotation of the camera. In alternative embodiments, the exposurecontroller 176 may preset rotation rate, CCD gain and/or line time(capture rate), or aperture (diaphragm) or slit width. To control theexposure of a digital capture device, such as a CCD, the controller 174stores in memory a value of the light sensor and uses the stored valueto set gain and/or line time. Gain is increased as light value isdecreased. Or line time is increased as light value is decreased. Bothgain and line time vary inversely with the sensor value.

Referring now to FIG. 9, generally designated at 180, 190, and 200 inFIGS. 9A, 9B, and 9C are diagrams useful in explaining the principles of"sinewave" exposure control of a panoramic camera in accord with thepresent invention.

Any outdoor panoramic scene illuminated by the sun at an angle otherthan at the zenith will be backlit, sidelit and frontlit such that thebacklit and frontlit scenes will lie one hundred eighty degrees (180)out of phase as illustrated by the exemplary rolled-out exposure diagram180 of FIG. 9A having a backlit rock at about ninety (90) degrees,having a sidelit igloo at about one hundred eighty (180) degrees and aperson frontlit at about two hundred seventy (270) degrees. For any suchpanoramic scene, the illumination of the side of the objects facing thecamera in the lower portion of the scene excluding the sky will alwaysbe at minimum and maximum values respectively where the scene is backlitand frontlit, except in the case of generally horizontal reflectingobjects, such as water. The sinewave diagram 190 of FIG. 9B shows thesinewave minimum and maximum respectively corresponding to the backlitrock at about ninety (90) degrees in FIG. 9A and to the frontlit personat about two hundred seventy (270) degrees in FIG. 9A. For any suchpanoramic scene, the overall brightness will vary with the declinationof the sun, such that the higher the sun is in the sky the more brightthe illumination on the scene, and the lower the sun the lesser thebrightness, and with the prevailing weather conditions, such that themore cloudy the less bright and vice versa. As appears more fully below,"sinewave" ambient light responsive exposure control of a panoramiccamera in accord with the present invention as shown by the controlsinewave 200 of FIG. 9C is achieved by adjusting the sinewave'samplitude to both the sun's declination and to the prevailing ambientlighting conditions, and by adjusting the sinewave's phase to match theangular position of the starting point of the lens of the panoramiccamera. In this manner, exposure is maximized in the most backlitportion of the scene and it is minimized in the most frontlit portionthereof

Referring now to FIG. 10, generally designated at 210 is a functionalblock diagram of one embodiment of a "sinewave" ambient light responsivecontroller of a panoramic camera in accord with the present invention. Asinewave controller 212 having the usual ROM and RAM, not shown, isoperatively connected to an I/O device 214, such as a keypad, and to anexposure controller 216. The exposure controller 216, like the exposurecontroller 176 (FIG. 8), may controllably vary rotation rate, CCD gainand/or line time (capture rate), or aperture (diaphragm) or slit width,among other things.

As appears more fully hereinbelow, in this embodiment, the amplitude ofthe sinewave is determined by the sinewave controller 212 in response tooperator keypad entry of information representative of the declinationof the sun and of information representative of the prevailing weatherconditions. The phase of the sinewave is determined by the sinewavecontroller 212 in response to operator keypad entry of informationrepresentative of the position of the sun in the plane of rotation ofthe camera relative to the starting angular position of the lens of thepanoramic camera. The exposure controller 216 is responsive to saidsinewave of amplitude that corresponds to the sun's declination andprevailing weather conditions and of phase that corresponds to angularposition of the sun in the plane of rotation of the camera relative tothe len's starting position to control the exposure of the panoramicscene so as to compensate for the variation in lighting encounteredabout the panoramic scene.

Referring now to FIG. 11, generally designated at 220 is a pictorialview of a sun protractor having declination rings useful with the FIG.10 embodiment of a "sinewave" ambient light responsive controller of apanoramic camera in accord with the present invention. The sunprotractor 220 includes a graduated protractor ring 222, that alsoserves as a sun declination ring, one or more concentric sun declinationrings 224, and a gnomon 226. The sun declination rings 222 eachcorrespond to another "stop," where one stop equals a doubling or ahalving of exposure. The rings are printed or otherwise providedpreferably on a specular surface generally designated 228 mounted forrotation with the panoramic camera, not shown, although they may beprovided separably of the camera so long as the relative orientations ofcamera lens and protractor are preserved. The lens of the panoramiccamera is schematically illustrated by box 230 at the (0/360) degreemark.

To obtain the phase of the sinewave that matches the angular position ofthe sun in the plane of camera rotation relative to the starting pointof the lens, the operator notes the angular position of the shadow thegnomon 226 casts on the projector ring 222 relative to the lens startingposition, illustrated at about three hundred (300) degrees, and entersit to the keypad 214 (FIG. 10). To obtain the amplitude of the controlsinewave that matches the sun's declination, the operator notes whichdeclination ring the tip of the shadow cast by the gnomon 226 is at ornear, and enters it to the keypad 214 (FIG. 10). To refine the amplitudeof the control sinewave that matches the prevailing weather conditions,the operator may note which one of "clear," "partly cloudy," "overcast,"or "deep shade" (or other preprogrammed) conditions most closely matchesthe prevailing conditions, and enters it to the keypad 214 (FIG. 10).The sinewave controller 212 (FIG. 10) responds to the manually enteredinformation and produces a control sinewave corresponding thereto. Theexposure controller 216 (FIG. 10) responds to the control sinewaveprovided by the sinewave controller to controllably vary exposure toaccommodate the variations in lighting encountered about the panoramicscene.

On cloudy days when the shadow of the gnomon 226 is not cast or isbarely cast, the operator looks into the specular surface 238 and movesaround until a bright spot corresponding to the sun is collocated withthe image of the tip of the gnomon, notes the angular position thereofon the protractor ring 222 and the declination ring which it is at ornear, and sequentially enters the information on the keypad 214 (FIG.10). The sinewave controller 212 (FIG. 10) responds to the manuallyentered information and produces a control sinewave correspondingthereto. The exposure controller 216 (FIG. 10) responds to the controlsinewave provided by the sinewave controller to controllably varyexposure to accommodate the variations in lighting encountered about thepanoramic scene.

Referring now to FIG. 12, generally designated at 240 is a functionalblock diagram of another embodiment of a "sinewave" ambient lightresponsive controller of a panoramic camera in accord with the presentinvention. A sinewave controller 242 having the usual ROM 246 and RAM248 is operatively connected to an I/O device 250, such as a keypad, andto an exposure controller 252. The RAM 248 (or ROM) may be provided withtable look up to enable the operator to retrieve the latitude andlongitude of the panoramic site by keypad entry. The exposure controller252, like the exposure controller 176 (FIG. 8) and the exposurecontroller 216 (FIG. 10), may controllably vary rotation rate, CCD gainand/or line time (capture rate), or aperture (diaphragm) or slit width,among other things.

The controller 242 is operatively connected to a time and date clock254, a GPS system 256, and to an electronic compass 258.

In operation, the sinewave controller 242 is responsive to time and dateinformation provided by the clock 254, to information representative ofthe latitude and longitude coordinates provided by the GPS 256, and toinformation representative of the bearing coordinates provided by theelectronic compass 258 to determine the angular phase of the sinewave inthe plane of rotation of the panoramic camera relative to the startinglocation of the lens. In an alternative embodiment, informationrepresentative of the latitude and longitude coordinates may be providedby table look up from the RAM 248 in response to operator entry of thecity or other scene location on the keypad 250. The controller 242 isalso responsive to the GPS (or table look up) information and to theclock information to determine solar declination, as well as toinformation manually entered on the keypad 250 representative of theprevailing weather conditions, such as "cloudy" or "bright," from whichthe amplitude of the control sinewave determined. The exposurecontroller 252 responds to the control sinewave provided by the sinewavecontroller 242 to controllably vary exposure to accommodate thevariations in lighting encountered about the panoramic scene.

It is to be noted that the control sinewave provided by the embodimentsof the FIGS. 10-12 may be used to approximate the overall exposurefairly accurately in addition to the corrections to it along therotational path without reliance on a light metering system, saidexposure being used independently or in combination with an overallexposure arrived at by a light metering element such as the incidentlight measuring dome on top of the camera measuring general incidentlight conditions. In addition, it is to be noted that the controlsinewave provided by the embodiments of the FIGS. 10-12 may be usedtogether with the signal (whether stored or in real time) of any of thelight sensor embodiments described herein to control exposure. Forexample, gross over exposure of a sunset may be avoided by the includedweighting of a frontally mounted reflective light sensor, such as bysimple averaging of the two signals.

Many modifications of the instant invention may be made withoutdeparting from the scope of the appended claims. For example, the use ofa cold mirror (one which reflects visible light and transmits infrared)as the specular member, or members of the virtual axis panoramic cameragreatly reduces the infrared component of the incoming light obviatingthe use of special filters or light sources. This is particularlyimportant in the case of CCD cameras where the imaging chip is moresensitive to infrared light than to the visible and the filters used toseparate colors are not efficiently opaque to infrared light, therebyresulting in a contamination of visible light component images by anoverlay of an infrared image causing a distortion of values and loss ofcolor contrast and purity. In an alternative embodiment, in the case ofa prism as a specular member displacing the image, the body of the prismcould be of a material which absorbs infrared (such as the materialknown as `heat absorbing glass`) and the reflective surfaces of theprism or prisms could also be coated with a cold mirror coating furthereliminating the infrared light component. It will be appreciated thatthe scan of the panoramic camera of the invention may be a full threehundred and sixty degree (360) scan or any angular part thereof. Itwill, of course, be appreciated by those of skill in the art that any ofthe controller devices described herein have the usual interfacesallowing the operator to input lens aperture, film speed and overallplus or minus exposure bracketing adjustment thereinto. It should alsobe noted that waveforms other than control sinewaves may be employed solong as there are no transitions steep enough so as to be conspicuous.It is also to be noted that a second point or node of the gnomon may beindexed by placing a bead or other shadow casting means to expand therange of readable stops. It is also to be noted that GPS, table look up,the sun protractor and declination rings are exemplary only, and thatother methods and means may be employed to obtain the amplitude andphase of the control sinewave or other control waveform in accord withthe present invention.

What is claimed is:
 1. A panoramic camera providing automatic exposurecontrol, comprising:a camera housing; an optical assembly including alens mounted to said camera housing and having an optical axis thatpoints along a linear direction; means for sweeping said lineardirection that said optical axis points about a panoramic field of view;means cooperative with said lens for exposing images of a panoramicsubject as said optical axis of said optical assembly is swept aboutsaid panoramic field of view; means for providing a signalrepresentative of existing lighting conditions including a light sensorand at least a one degree of freedom swivel mount to which said lightsensor is mounted enabling the light sensor to be pointed anywhere alongthe one or more directions provided by said at least one degree offreedom swivel mount operative in at least a reflected sensor mode,where said sensor is pointed in generally the same direction that thelinear direction of said optical axis of said lens points, and in anincident sensor mode, where said sensor is pointed in generally theopposite direction that the linear direction of said optical axis ofsaid lens points; and means cooperative with said images exposing meansfor controlling the exposure in dependence on said signal as saidoptical axis of said optical assembly is swept about said panoramicfield of view.
 2. The panoramic camera of claim 1, wherein said imagesexposing means includes film, wherein said sweeping means includes amotor, and wherein said exposure controlling means includes a motorcontroller coupled to said motor of said sweeping means and responsiveto a single reading of said signal to preset the rate at which saidoptical axis of said optical assembly is swept about said panoramicfield of view so as to provide constant exposure of said film about thepanoramic sweep.
 3. The panoramic camera of claim 1, wherein said imagesexposing means includes a digital image recording device having anamplifier for controlling digital image recording device gain, andwherein said exposure controlling means includes a gain controllercoupled to said amplifier for controlling digital image recording devicegain of said images exposing means responsive to said signal to presetsaid digital image recording device gain so as to provide constantexposure about the panoramic sweep.
 4. The panoramic camera of claim 1,wherein said images exposing means includes a digital image recordingdevice having an input for controlling digital image recording deviceline time, and wherein said exposure controlling means includes a linetime controller coupled to said input for controlling digital imagerecording device line time of said images exposing means responsive tosaid signal to preset said digital image recording device line time soas to provide constant exposure about the panoramic sweep.
 5. Thepanoramic camera of claim 1, wherein said images exposing means includesa digital image recording device having an amplifier for controllingdigital image recording device gain, and wherein said exposurecontrolling means includes a gain controller coupled to said amplifierfor controlling digital image recording device gain of said imagesexposing means responsive to said signal to govern said digital imagerecording device gain so as to provide continuously variable exposureabout the panoramic sweep.
 6. The panoramic camera of claim 1, whereinsaid images exposing means includes a digital image recording devicehaving an input for controlling digital image recording device linetime, wherein said signal representative of existing lighting conditionsproviding means includes a light sensor, and wherein said exposurecontrolling means includes a line time controller coupled to said inputfor controlling digital image recording device line time of said imagesexposing means responsive to said signal to continuously vary saiddigital image recording device line time so as to provide continuouslyvariable exposure about the panoramic sweep.
 7. A panoramic cameraproviding automatic exposure control, comprising:a camera housing; anoptical assembly including a lens mounted to said camera housing andhaving an optical axis that points along a linear direction; a motorizedrotating mechanism operatively coupled to at least one of said camerahousing and said optical assembly such that said linear direction thatsaid optical axis points is swept about a panoramic field of view; animage capture device cooperative with said lens exposing images of apanoramic subject as said optical axis of said optical assembly is sweptabout said panoramic field of view; a light sensor providing a signalrepresentative of existing lighting conditions relative to the angularphase of the panoramic field of view as said optical axis of saidoptical assembly is swept about its panoramic field of view; and anexposure controller including a processor cooperative with said imagecapture device controllably varying the exposure generally in inversedependence on said signal as said linear direction sweeps.
 8. Apanoramic camera providing automatic exposure control, comprising:acamera housing; an optical assembly including a lens mounted to saidcamera housing and having an optical axis that points along a lineardirection; means for sweeping said linear direction that said opticalaxis points about a panoramic field of view; means cooperative with saidlens for exposing images of a panoramic subject as said optical axis ofsaid optical assembly is swept about said panoramic field of view; alight sensor having a diffuser providing a signal taken at at least anacute angle to said linear direction of said optical axis of saidoptical assembly representative of lighting conditions generally abovesaid camera that is invariable with variations in the direction thatsaid optical axis of said optical assembly points as it is swept aboutits panoramic field of view; and means cooperative with said imagesexposing means for controlling the exposure in dependence on said signalas said optical axis of said optical assembly is swept about saidpanoramic field of view.